Definition 3.61 [1]}
Let \({C}, {D}, {E}\)  be model categories, and let \(\otimes \colon {C}\times {D}\rightarrow {E}\)  be an adjunction of two variables.
Then, \(\otimes \)  is a Quillen adjunction of two variables if the induced pushout product \(f,g \mapsto f \square g\)  satisfies the pushout-product axiom:
